gms | German Medical Science

Introduction: Increasing evidence suggests that microRNAs play a key role in the initiation and progression of cancer, and, therefore, may comprise a novel class of molecular biomarkers with prognostic and predictive potential. For colon cancer, several miRNA profiles have been published, however, data about miRNA regulation in rectal cancer are rare.

Materials and methods: RNA was extracted from tumor biopsies and normal adjacent mucosa from 72 patients with locally advanced rectal cancer). Each sample’s microRNA expression pattern was assayed on an LNA (Locked Nucleic Acid) enhanced microarray platform. To assess the relevance of differentially expressed miRNAs as blood-based biomarker, certain miRNAs were isolated from the plasma of 35 rectal cancer patients and 10 healthy controls using a modified Trizol protocol.

Results: More than 200 miRNAs were differentially expressed between rectal cancer and normal adjacent tissue (p<10-6). Some of the most significantly deregulated miRNAs were miR-143, miR-145, miR-21, miR-223, and members of the let-7 family, which have previously been reported to be specific for colon cancer. We also identified a subset of miRNAs that appear to be specific to rectal cancer. Out of 15 miRNA that were specifically upregulated in the tumor, none proved to be a blood-based biomarker for rectal cancer.

Conclusion: This study, for the first time, demonstrates a rectal cancer specific microRNA profile.